<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>闭包</title>
</head>

<body>
  <script type="text/javascript">
    function fn1() {
      var a = 2
      function fn2() {
        a++
        console.log(a)
      }
      return fn2
    }
    var f = fn1()
    f()
    f()
    f = null

  </script>
</body>

</html>